scholarly journals CFD Simulation of Aeration and Mixing Processes in a Full-Scale Oxidation Ditch

Energies ◽  
2020 ◽  
Vol 13 (7) ◽  
pp. 1633 ◽  
Author(s):  
Thomas Höhne ◽  
Tural Mamedov
Keyword(s):  
Fluid Flow ◽  
Cfd Simulation ◽  
Pure Water ◽  
Three Dimensional ◽  
Continuous Phase ◽  
Full Scale ◽  
Solid Particles ◽  
Mixing Processes ◽  
Treatment Processes ◽  
Sst Turbulence Model

This study aims to build a computational fluid dynamics (CFD) model that can be used to predict fluid flow pattern and to analyse the mixing process in a full-scale OD. CFD is a widely used numerical tool for analysing, modelling and simulating fluid flow patterns in wastewater treatment processes. In this study, a three-dimensional (3D) computational geometry was used, and the Eulerian-Eulerian multiphase flow model was built. Pure water was considered as the continuous phase, whereas air was modelled as the dispersed phase. The Shear Stress Transport (SST) turbulence model was specified which predicts turbulence eddies in free stream and wall-bounded region with high accuracy. The momentum source term approach and the transient rotor-stator approach were implemented for the modelling of the submersible agitators. The hydrodynamic analysis was successfully performed for four different scenarios. In order to prevent the incorrect positioning of the submerged agitators, thrust analysis was also done. The results show that the minimum required water velocity was reached to maintain the solid particles suspended in the liquid media and adequate mixing was determined.

CFD Study on must of Grapes Separation in a Hydrocyclone

2013 ◽  
Vol 837 ◽  
pp. 645-650
Author(s):  
Petru Cârlescu ◽  
Ioan Tenu ◽  
Marius Baetu ◽  
Radu Rosca
Keyword(s):  
Cfd Simulation ◽  
Reynolds Stress Model ◽  
Continuous Phase ◽  
Solid Particles ◽  
Advanced Degree ◽  
Separation And Purification ◽  
Discrete Phase Model ◽  
Flow Rates ◽  
Discrete Phase ◽  
Simulation And Experiment

Abstract. Hydrocyclones are increasingly used in the food industry for various separation and purification. In this paper, an optimization was made to design a hydrocyclone model using CFD (Computational Fluid Dynamics). CFD simulation is performed with FLUENT software by coupling the Reynolds Stress Model (RSM) for must of grapes flow with Discrete Phase Model (DPM) for solid particles trajectory. Coupling of discrete phase (particles) and continuous phase (must of grapes) in the mathematical model is set so that the continuous phase to influence discrete phase. Tracking particles traiectory in this hydrocyclone allows advanced degree is separation so obtained to the maximum particle size approaching the size of a yeast cell 10 μm, without separating them. Hydrocyclone dimensional designed simulation was performed and analyzed on an experimental pilot plant for three different must flow rates supply. Introduced particle flow rates simulation and experiment does not exceed 10% of the must flow rates. The degree of separation obtained is in agreement with experimental data.

scholarly journals ANALYSIS OF THE NUMERICAL MODELLING OF TURBULENCE IN THE CONICAL REVERSE-FLOW CYCLONE

2010 ◽  
Vol 2 (5) ◽  
pp. 17-22
Author(s):  
Inga Jakštonienė ◽  
Petras Vaitiekūnas
Keyword(s):  
Fluid Flow ◽  
Numerical Modelling ◽  
Reverse Flow ◽  
Three Dimensional ◽  
Cylindrical Part ◽  
Solid Particles ◽  
Good Prediction ◽  
Transfer Equations ◽  
Volume Method ◽  
Tangential Inlet

The paper describes the numerical modelling of the swirling fluid flow in the Stairmand cyclone (conical reverse-flow – CRF) with tangential inlet (equipment for separating solid particles from the gaseous fluid flow). A review of experimental and theoretical papers is conducted introducing three-dimen­sional differential equations for transfer processes. The numerical modelling of the Stairmand cyclone the height of which is 0.75 m, diameter – 0.17 m, the height of a cylindrical part – 0.290 m, a conical part – 0,39 m and an inlet area is 0,085×0,032 m is presented. When governing three-dimensional fluid flow, transfer equations Navje-Stokes and Reynolds are solved using the finite volume method in a body-fitted co-ordinate system using standard k– e and RNG k– e model of turbulence. Modelling is realised for inlet velocity 4.64, 9.0 and 14.8 m/s (flow rate was 0.0112, 0.0245 and 0.0388 m3/s). The results obtained from the numerical tests have demonstrated that the RNG k– e model of turbulence yields a reasonably good prediction for highly swirling flows in cyclones: the presented numerical results (tangential and radial velocity profiles) are compared with numerical and experimental data obtained by other authors. The mean relative error of ± 7,5% is found.

Comparison of CFD Simulation to the Experiments for Forward Step Flows

2003 ◽  
Author(s):  
Shoichiro Nakamura ◽  
Hiroyuki Onuma ◽  
Peter G. Carswell
Keyword(s):  
Fluid Flow ◽  
Vortex Shedding ◽  
Cfd Simulation ◽  
Computational Simulation ◽  
Three Dimensional ◽  
Flow Simulation ◽  
Unsteady Motion ◽  
Computational Results ◽  
Over The Top ◽  
Unsteady Behavior

Three dimensional DNS simulation on the fluid flow over a forward step configuration are compared with the experiments reported by Shakouchi, Ando, and Ito. This is a part of authors’ attempts to evaluate the validity of three dimensional unsteady flow simulation by comparison to experiments. Summary of the comparison is as follows: (1) vortex shedding in the flow separation over the top of the step near the corner is observed, (2) frequency of vortex shedding and distance between two consecutive vortices do not agree with the experiment, (3) however, while steady periodic shedding of vortices from the top corner of the step is reported for the experimental results, the computational results show unsteady behavior of the flow over the top corner, which results in unsteady shedding of vortices. This unsteadiness in the computational simulation is due to unsteady motion of fluid upstream from the step where adverse pressure increase occurs.

scholarly journals Unsteady CFD simulation of 3D AUV hull at different angles of attack

2016 ◽  
Vol 13 (2) ◽  
pp. 111-123
Author(s):  
Sudipta Ray ◽  
Dipankar Chatterjee ◽  
Sambhunath Nandy
Keyword(s):  
Cfd Simulation ◽  
Autonomous Underwater Vehicle ◽  
Turbulent Transport ◽  
Three Dimensional ◽  
Flow Simulation ◽  
Underwater Vehicle ◽  
Three Dimensional Flow ◽  
Pressure Coefficients ◽  
Hydrodynamic Parameters ◽  
Sst Turbulence Model

An unsteady, three-dimensional flow simulation is carried out over the bare hull of the autonomous underwater vehicle currently being developed by CSIR-CMERI, Durgapur, India at various angles of attack with the help of a Finite Volume-based CFD software. The purpose of the study is to provide estimation of various hydrodynamic forces acting on the bare hull at different angles of operation. The operating range of velocity of the vehicle is 0-6 knot (0-3 m/s), considering up to 2 knots of upstream current. For the purpose of the CFD simulation, the widely-implemented RANS approach is used, wherein the turbulent transport equations are solved using the low-Re version of the SST ?-? turbulence model. The motion of the vehicle is considered within a range of the pitch angle (0<=alpha<=20). The results are presented in terms of variations of the relevant hydrodynamic parameters. The effects of the angle of attack on the drag and pressure coefficients are discussed in detail.

scholarly journals Numerical Simulation of Full-Scale Three-Dimensional Fluid Flow in an Oscillating Reactor

2021 ◽  
Vol 9 ◽  
Author(s):  
Houjun Gong ◽  
Mengqi Wu
Keyword(s):  
Numerical Simulation ◽  
Fluid Flow ◽  
Flow Field ◽  
Flow Rate ◽  
Three Dimensional ◽  
Flow Characteristics ◽  
Full Scale ◽  
Variation Patterns ◽  
Oscillating Motion ◽  
Resistance Coefficients

Marine reactors are subjected to additional motions due to ocean conditions. These additional motions will cause large fluctuation of flow rate and change the coolant flow field, making the system unstable. Therefore, in order to understand the effect of oscillating motion on the flow characteristics, a numerical simulation of fluid flow is carried out based on a full-scale three-dimensional oscillating marine reactor. In this study, the resistance coefficients of the lattice, rod buddle and steam generator are fitted, and the distribution of flow rate, velocity as well as pressure in different regions is investigated through the standard model. After additional oscillation is introduced, the flow field in an oscillating reactor is presented and the effect of oscillating angle and elevation on the flow rate is investigated. Results show that the oscillating motion can greatly change the flow field in the reactor; most of the coolant circulates in the downcommer and lower head with only a small amount of coolant entering the core; the flow fluctuation period is consistent with the oscillating period, and the flow variation patterns under different oscillating conditions are basically the same; since the flow amplitude is related to oscillating speed, the amplitude of flow rate rises when decreasing the maximum oscillating angle; the oscillating elevation has little effect on the flow rate.

Determination of Outside Heating Distribution Using an Inverse Algorithm for an Industry Hydrothermal Autoclave With Three-Dimensional Flows

2004 ◽  
Author(s):  
Hongmin Li ◽  
Minel J. Braun ◽  
G.-X. Wang ◽  
Edward A. Evans
Keyword(s):  
Heat Transfer ◽  
Heat Flux ◽  
Fluid Flow ◽  
Heat Conduction ◽  
Flux Distribution ◽  
Cfd Simulation ◽  
Three Dimensional ◽  
Heat Flux Distribution ◽  
Inverse Algorithm ◽  
Small Magnitude

Hydrothermal growth is the industry method of preference to obtain high quality single crystals. Due to the high pressure and high temperature growth conditions, growth process is carried out in closed containers. During a growth run, the only flow and heat transfer that control crystal growers have is the outside heating. An inverse algorithm, used to obtain the heating distribution for an autoclave with a two-dimensional flow, is further developed and used to determine the heating distribution for an industry autoclave with three-dimensional flows. A cross-section area average temperature distribution is set as a target. With the three steps, including CFD simulation of the fluid flow, heat conduction in the metal wall, and heat conduction in the insulation layer, the heater heat flux distribution is determined. The distributions appear close to linear from the median height to the top/bottom with small magnitude deviation in the circumferential direction. Linearly distributed heaters, based on the determined heat flux distribution, are then used and heat transfer and fluid flow is numerically simulated with a conjugate model. The achieved temperature agrees well with the targeted one. The distribution and heating rates of linearly distributed heaters can be applied to industry autoclaves.

Transient DEM-CFD simulation of solid and fluid flow in a three dimensional blast furnace model

2018 ◽  
Vol 334 ◽  
pp. 53-64 ◽  
Author(s):  
F. Bambauer ◽  
S. Wirtz ◽  
V. Scherer ◽  
H. Bartusch
Keyword(s):  
Blast Furnace ◽  
Fluid Flow ◽  
Cfd Simulation ◽  
Three Dimensional

Lattice Boltzmann Simulation of Suspended Solid Particles in Microchannels

2011 ◽  
Author(s):  
Zahra Hashemi ◽  
Omid Abouali ◽  
Reza Kamali
Keyword(s):  
Fluid Flow ◽  
Lattice Boltzmann ◽  
Three Dimensional ◽  
Suspended Solid ◽  
Solid Particles ◽  
Lattice Boltzmann Model ◽  
Momentum Exchange ◽  
Rectangular Microchannel ◽  
Exchange Method ◽  
Suspended Solid Particles

The current paper presents a 3D Lattice Boltzmann model for numerical simulation of the interaction of the suspended solid particles with the flow field in microchannels. Three-dimensional fluid flow computation is performed using a 19-bit single-relaxation-time Lattice Boltzmann method (D3Q19), while the Newtonian dynamic equations are solved to investigate the transport of the suspended solid particles. The needed forces in equations of the particle motion are evaluated by the momentum exchange method. The effects of solid particles with various diameters on the fluid flow at different Reynolds numbers in a rectangular microchannel are also investigated and discussed.

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